如何探出对方价格底线

Dan提议前半年给对方二成折扣，后半年再降为一成半，经Robert推翻后，Dan再三表示让步有限。您知道Robert在这折扣缝隙中游走，如何才能摸出双方都同意的数字呢？他从锦囊里又掏出什么妙计了呢？请看下面分解：

R: How about 15% the first six months, and the second six months at 12%, with a guarantee of 3000 units?

D: Thats a lot to sell, with very low profit margins¹.

R: Its about the best we can do, Dan. (pause) We need to hammer something out （敲定）today. If I go back empty-handed, I may be coming back to you soon to ask for a job. (smiles)

D: (smiles) O.K., 17% the first six months, 14% for the second?!

R: Good. Lets iron out（解决）the remaining details. When do you want to take delivery（取货）?

D: Wed² like you to execute the first order by the 31st.

R: Let me run through this again: the first shipment for 1500 units, to be delivered in 27 days, by the 31st.

D: Right. We couldn't handle much larger shipments.

R: Fine. But I'd prefer the first shipment to be 1000 units, the next 2000. The 31st is quite soon ---- I can't guarantee 1500.

D: I can agree to that. Well, if there's nothing else, I think we've settled everything.

R: Dan, this deal promises big returns（赚大钱）for both sides. Let's hope its the beginning of a long and prosperous relationship.